This invention relates to degassing of liquids and has particular application for the degassing of drilling muds.
As oil well drilling mud has become more and more sophisticated and the overall operation of the well drilling more and more automated, mud handling equipment has been sought to efficiently, quickly and automatically process mud for reuse. One of the necessary operations under certain well conditions is the removal of gas from the mud returning from the well bore. Gas cut mud can be a problem both in the well bore and in various treating apparatus. In the well bore, the lighter gas can result in head loss in the well. In treatment apparatus, the gas causes major cavitation problems when pumped. Gas-cut mud is intended to mean a mixture of liquid and gas including gas bubbles and entrained gas which may be dissolved. In many instances, the gasses are toxic and require controlled venting away from personnel.
Consequently, devices have been developed for the degassing of mud to overcome these problems. Two commercial types of degassers have found acceptance. The first type spreads a thin sheet of mud over a large surface area across a plate or plates in the presence of a vacuum for extraction of gas entrained in the mud.
The second type of degasser commercially accepted at the present time is a device which operates on the principle of violently throwing the mud in a radial direction outwardly to splash against the interior walls of a cylinder. In this second type of degasser, the throwing of the mud and its impacting on a surface present the gas contained within the body of the mud to the surrounding atmosphere for dissipation.
In spite of the commercial acceptance of these approaches, the need remains for more efficient, energy conservative systems. Substantial amounts of money can be saved by attention to the maximizing of efficient operation. In the thin-sheet/vacuum systems only a small amount of the total energy consumed is imparted to make the gas available for separation. Considerable energy is, in effect, wasted because of the pumping systems required to propel mud through such equipment. In the splash-type systems, less than adequate degassing results when treating heavily gas-cut mud because of efficiency losses in the direct centrifugal pumping systems required to feed such systems.